Sulfosuccinates are a class of surfactants based upon sulfosuccinic acid. There are two types of sulfosuccinate: half ester (or monoester) and diester. These two types of sulfosuccinate are shown below, with sodium as the cation. It is, however, known that other cations may also be used instead of sodium to provide the neutralised salt product, such as potassium, magnesium or ammonium.

The sulfosuccinates can also be classified into two main groups based on the starting materials used for their manufacture: (i) fatty alkanolamide (including alkoxylated alkanolamide) derived sulfosuccinates, and (ii) fatty alcohol (including alkoxylated alcohol) derived sulfosuccinates. These starting materials affect the R group in the sulfosuccinate.
The half ester sulfosuccinates are well known for use as mildness additives, foam boosters and rheology modifiers in skin and hair care products, such as shampoo and facial and body washes. The diester sulfosuccinates are better known as industrial wetting agents, dispersants and emulsifiers.
Typical half ester sulfosuccinates are prepared by reacting a fatty alkanolamide (or ethoxylated fatty alkanolamide) or a fatty alcohol (or ethoxylated/propoxylated fatty alcohol) with maleic anhydride to form an intermediate half ester. The intermediate half ester is then reacted with a bisulfite (e.g. sodium or potassium bisulfite) to form the sulfosuccinate.
The diester sulfosuccinates are made by a similar process, but with two equivalents of the fatty alkanolamide, ethoxylated alkanolamide, fatty alcohol or ethoxylated and/or propoxylated alcohol being reacted with maleic anhydride to form an intermediate diester, which is then reacted with a bisulfite (e.g. sodium or potassium bisulfite) to form the diester sulfosuccinate.
An example reaction scheme for the preparation of a half ester sulfosuccinate from a fatty alkanolamide is shown in FIG. 1.
It is well known that steel and other metal surfaces can corrode in the presence of aqueous environments; especially acidic aqueous environments such as those found in subterranean wells, which can pass through formations containing high concentrations of corrosive materials such as hydrogen sulphide, carbon dioxide, brine, and the like.
Alloy technology and galvanisation have resulted in materials that can withstand some incidental contact with corrosive environments, but in a number of industrial applications (such as hydrocarbon exploration, recovery and refining, and chemical processing) more prolonged contact with corrosive environments occurs. In particular, during the working life of an oil or gas well various conduits and other components in the production zone encounter considerable acidic corrosion.
Corrosion inhibitors are therefore widely used in oil and gas production wells and pipelines to reduce corrosion of metal components and therefore prevent consequential production equipment failures.
Imidazolines are commonly used as corrosion inhibitors, and are viewed as the industry standard, but are known to have poor aquatic toxicity.
There is therefore a continuing need for corrosion inhibitors, for use in the oil and gas industry and other industrial applications, which have improved aquatic toxicity and biodegradability.